Audio signals are captured in analogue form and the first stage in a modern digital multimedia system is to convert the analogue signal into a discrete time form. (a) Briefly describe the process of quantization of an audio signal, specifying if/when the process is reversible. (4 marks) (b) Consider the case of a speech signal and provide the bit rate obtained after sampling and quantization (assume you represent each sample with 8 bits). (5 marks) (c) Assume a waveform represented by one sinusoid of frequency 5 kHz. (1) Determine any alias components when the waveform is sampled at a rate of (1) 12 k samples per second. (2) 7 k samples per second. Illustrate the result with a drawing (5 marks) (d) Calculate the file size for a ten-minute stereo CD quality audio track. (6 marks) (Total 20 marks)